Nick, most racing classes have a minimum weight that you have to meet when you come off the track. They are set so that most everyone will have to add weights to meet the minimum.
Also, while you might not have a shop with in 30mins of you…you are in a very central location for karting. LA has several shops and clubs. Bakersfield has a club…not sure if there is still a shop…and Santa Maria also has a club…no shop…but most of the members are very willing to help out new people. Lancaster has/will have a club also.
My suggestion would be to mount the seat per the chassis manufacture recommendations. Then get a TON of seat time.
Sebastian, As long as you have enough clearance for the motor and/or clutch you can move the right side seat mount if you need to.